Agricultural combines are large machines that harvest, thresh, separate, and clean agriculturally planted harvested crop that carry corn. The cleaned corn, so obtained, is stored in a corn tank on the combine. As a rule, the threshed-out straw is either chopped and distributed on the field across the width of the cutter head or conducted around the straw chopper and deposited in a swath on the field without being chopped, in order to pick it up subsequently with a baler. The harvested crop residue remaining at the rear outlet of the cleaning arrangement, such as chaff and small straw particles, is distributed across the field by a chaff spreader or is conducted through the straw chopper and distributed across the field.
DE 199 08 111 C and DE 101 33 965 A describe combines with a straw chopper and two impeller blowers, arranged side by side alongside each other, that follow the straw chopper for the widely distributed straw ejection across the field. The outlet of the straw chopper and the inlet of the impeller blowers are arranged in a housing, that include impeller blades rotating about an approximately vertical axis and are arranged in a plane for the sake of unidirectional harvested crop transfer. The impeller blades are fastened to a central circular cylindrical shaft underneath a cover plate and are brought into rotation by a drive element arranged above the cover plate.
EP 1 074 175 A and US 2007/0015556A that is seen as establishing a class, describe impeller blowers in which the straw is thrown against the impeller blowers by means of an ejection drum without being chopped at an angle to the combine from above (EP 1 074 175 A) or through a straw chopper in the chopped form at an angle to the combine from below (US 2007/0015556A), the impeller blowers are built up by impeller blades on a circular disk and extend radially and vertically to the surface of the disk. The blades are configured in a wedge shape, where the outer ends of the blade have a greater vertical length than the inner ends of the blades. No blades are provided in the area of the axis of rotation. In EP 1 074 175 A, cylindrical bodies are located therethrough which the shaft driving the impeller blowers extends, while according to US 2007/0015556 A, a pot shaped attachment for the shaft is located there.
DE 100 63 554 A describes a combine with a straw chopper that rotates about a vertical axis and includes a conical body about whose circumference the chopper knives are attached in a spiral arrangement.
U.S. Pat. No. 1,625,353 A describes a combine whose straw shakers eject the straw without chopping it onto an impeller blower with a vertical axis of rotation. The impeller blower includes a conical disk, with blades arranged at its outer edge that extend vertically and radially to the outside.
As already noted, in the arrangement according to DE 199 08 111 C the outlet of the straw chopper and the inlet of the impeller blower are arranged in a single plane. However, such an arrangement has a disadvantage since the material delivered at the circumference of the straw chopper is inadequately engaged by the impeller blower, since only an (upper) part of it interacts with the lowest part of the impeller blade, while the remaining material falls to the ground. To avoid this problem, circular disks are attached underneath the impeller blades that rotate with the impeller blades, according to DE 101 33 965 A.
If the disk underneath the impeller blades were omitted in order to avoid the aforementioned problem and a non orthogonal angle between the axis of rotation of the impeller blower and the plane of the outlet of the straw chopper were provided, as is known from US 2007/0015556 A, a considerable part of the harvested crop would be thrown against the inner regions of the blades and towards the axis of rotation by the straw chopper, which would result in a problematical delivery of the harvested crop on the basis of the lower centrifugal force existing there and the missing impeller blades in the area of the axis of rotation. This problem also exists in the case of the arrangements according to EP 1 074 175 A and US 2007/0015556 A.
DE 100 63 554 A refers to only one straw chopper and cannot contribute to the solution of this problem, since it does not concern itself with the transition of the harvested crop residue from a straw chopper to an impeller blower, this is the same as U.S. Pat. No. 1,625,353 A that describes only one impeller blower.